The president of Iran has broken new ground by tweeting a photo of a female mathematician without a hijab. His decision prompted a powerful reaction on social media.

The mathematician in question - Maryam Mirzakhani - is Iranian, and recently became the first woman to win the Fields Medal for her pioneering work in the field. President Rouhani tweeted a message expressing his delight at the news. "Congrats to #MaryamMirzakhani on becoming the first ever woman to win the #FieldsMedal, making us Iranians very proud," he said. The surprise came by way of two pictures he attached to the message. In one half the mathematician appeared wearing a hijab - required by law for women in Iran, and in the other she appeared bare-headed. The image has been retweeted almost 3,000 times, and caused a deluge of comments online.

Many criticised the gesture as hypocritical. "Will you encourage women in Iran to study and be successful like her? Or are you gonna oppress them like always?" said one. "#Iran diaspora so excited abt Prez Rouhani's use of Mirzakhani pics; Silent as women increasingly banned from various fields in universities," said another, referring to a range of restrictions placed the subjects women could study two years ago.

It's been suggested that Rouhani was sending a message to highly qualified Iranian women, in an attempt to reverse the country's "brain drain". The response to the image on the president's alternative Farsi language Twitter account appeared to confirm that. "This will encourage young people in Iran. Don't let them to think that immigration is the only way," said one user. Tens of thousands of women have left the country in recent years to enhance their careers in Europe and North America. Indeed, Mirzakhani herself left the country after completing her undergraduate degree, and is now resident in the US.

Others felt the president was playing it safe. "It's probably to appease both sides... you'd be surprised how many trolls knock Muslim women for not wearing 'proper' attire," said one. Perhaps indicative of the more liberal tendencies of Iranians who use Twitter, very few expressed outrage at the decision.

Despite the president's bold move, the national press did not feel it could follow suit. The Iran Newspaper ran a single - covered - photo of Mirzakhani, and others ran clever crops or illustrations to dodge this issue. Showing uncovered women is a red line in the Iranian media that is rarely crossed, for fear of being accused of insulting the hijab, or promoting anti-Islamic values.

The front page of Thursday's Iran Newspaper

Rouhani has previously suggested he would take a softer line on the Islamic dress code. In July last year he said he opposed a crackdown against women with loose clothing. Earlier this year many women in the country flouted the law, by posting images of themselves without hijabs on Facebook.

BBC links

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.